'86 honda ...want to hook up head unit!

I just bought an '86 Honda civic hatchback DX. The radio was missing but it seems like i found a set of wires with all sorts of colors (wires which are really thin in thickness) and it's all bunched up...

are these the radio wires? I have a Pioneer Deh-p4400 and i want to hook it up to this car but i dunno how.

also the cars battery is small.....not the like the one in my toyota camry 2000....

so i dunno if i can hook up two 12" infinity subs with a sony amp and the head unit..i dunno if it'll power it cuz i dunno if there's a strong enough alternator.